Wet felt for the paper and pulp industry



Patented Feb. 23, 1926.

EDUARD v. ASTEN', F EUPEN, BELGIUM.

WET FELT FOR THE PAPER AND run? INDUSTRY.

Nonrawing.

To all whom it may concern:

Be it known that I, EDUARD v. As'rnN, a subject of the King of Belgium, residing at Eupen, No. Hillstrasse, Belgium, have invented certain new and useful Improvements in \Vet Felts for the Paper and Pulp Industry, and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

l/Voollen wet-felts first and second press for the paper and pulp industry are hitherto made of carded wool-yarn, worsted woolyarn or of twined threads of worsted yarn and carded yarn.

Such felts are exposed to a heavy wear on the respective machines. They run through the pressing cylinders of the machines under a high pressure and are always strongly tightened in the longitudinal direction.

Their upper surface which is provided with a dense nap, rapldly wears out by the pres sure of the pressing cylinders, and the action of the felt cleaners arranged on the machines.

WVhen used for making felts, worsted yarn possesses over carded yarn the advantage of being stronger and more uniformly spun than the latter but the drawback of being harder and'its nap less soft than that of the carded yarn, so that felts of worsted yarn are liable tomake impressions of their structure, i. e. mark, on the wet paper. On the other hand, carded yarn is weaker than worsted yarn so that felts of carded yarn are less durable than felts of worsted yarn, but carded yarn is softer than worsted yarn and the danger of a felt of carded yarn marking on the paper web is therefore smaller.

Twined threads of worsted yarn and carded yarn unite the advantages but also the disadvantages of the two kinds of yarn.

Now, the invention has for its object to provide a felt which is strong and durable on the one hand and which possesses a soft outer surface on the other hand, all advantageous properties of the said kinds of yarn being thus united in the felt.

This object is attained according to the invention by making the felt of threads having an inner core of great strength and a soft outer surface. To this end, I use as core a thread of worsted yarn, i. e. finished yarn, and spin around this core roving of Application filed April 30, 1924. Serial No, 710,188.

worsted 'yarnwhich means yarn that-is not yet finished or twisted. The'strongyarn', VlZ worsted yarn, thus forms the core of the In the finishing of the felt, the core embedded in the interior of the thread according to the invention will not be affected by the raising action, but the nap will only be formed by the fibres of the envelope so that the core will remain untouched and thus retain its full strength. With felts of carded yarn, however, the uniform threads are acted upon throughout by the nap raising machines and their structure will therefore become loose.

A special advantage of the felt according to the invention resides in the fact that the pressure of the pressing cylinders which mainly causes the rapid wear of the felts, will become. less destructive inasmuch as it is rendered elastic by the soft envelopes surrounding the cores of the threads.

Another essential advantage of the present felt will be evident from the following. The specific weight of worsted yarn is higher than that of carded yarn, which means that a thread of worsted yarn of the same thickness as a thread of carded yarn is heavier than the latter and contains more wool-fibres because the same lie down in the thread, while with carded yarn it is impossible to obtain the same smooth drawing of the fibres. A thread of carded yarn is therefore thicker than a thread of worsted yarn of the same weight, and a fabric of carded yarn which contains yarns of the same weight as a similar fabric of worsted yarn, will therefore be'more densely woven than the latter. Now, with felts designed to be used on the first and second press of paper or the like machines it is of importance that Y the felt possesses an open structure so as to allow the water squeezed out of the paper to flow off. Comparing two equally open felts of carded yarn and worsted yarn, the latter will therefore be the heavier and stronger one. The

special threads used in accordance with the invention possess the same advantageous 5 properties as the worsted yarn.

Having thus described my invention, what I claim as new and desire to secure by Letters-Patent, is

1. A wet felt made up of threads, each 10 consisting of a core of worsted yarn with an envelope of roving of wool covering the same.

2. A wet felt made up of threads, each consisting of a core of worsted yarn with an envelope of roving of wool covering the same, and fulled to provide an interlocking of the fibres of the envelope as a loose per- Ineable felt about and while maintaining the full strength of the core, whereby to form a water permeable wet-felt of requisite tensile strength.

In testimony whereof I have signed my name to this specification.

EDUARD V. ASTEN. 

